I am thinking of switching from Final Cut Pro X (FCPX) to Adobe Premiere Pro (APP). What kind of video files can APP read? Can i import files and customize the resolution, Aspect ratio after importing files of a different size/AR? Do i need to render every 5 minutes? Is the program fast and responsive? Keyframes? Masking? Titles and FX? Usability?

I use PP5.5 on OSX on a daily basis for work (and used CS4 before that), so I can speak to most of this.

PP can read most common video formats, including Quicktime, AVCHD, RED, AVI (that QT can open, Perian helps), etc. You can adjust the resolution of files once they're on the timeline by scaling, though you're probably better off resizing before importing. You can easily adjust PAR on things after importing, though (Right-click/Ctrl-click on the item in the bin, Modify -> Interpret Footage (Just Interpret Footage in CS4), adjust as desired).

I very rarely ever need to render footage until the final export, my computer (slower than yours) is fast enough to play most effects in realtime. And even on the rare occassion I do need to render, it's as simple as setting the work area I want to render and pressing Enter. Keyframes and basic masking are quickly available through the Effects Control panel or the Effects bin. Keyframes can also be adjusted from the timeline with something that resembles the rubber bands of earlier Premiere versions, but I don't like that interface as much. Titles are available, though rather basic, IMO (I prefer to make my titles in PS and import instead). There's a decent stable of prebuilt effects, though.

For usability, FCP and PP ripped pieces of each other's interfaces off for years. If you've used FCP before X, it's not a huge jump to move to PP. The latest episode of Film Riot has the host (a longtime FCP user) talking about his experiences moving from FCP 7 to PP5.5.

LantisEscudo wrote: Keyframes can also be adjusted from the timeline with something that resembles the rubber bands of earlier Premiere versions, but I don't like that interface as much.

Okay, THAT is a little hard for me to comprehend. Do you have a screenshot of that?

Sure.

You select the property you want to adjust from the dropdown (default is opacity), then move the playback head to the frame you want to set a keyframe on, hit the center button on the Set/Jump panel to mark the frame as a keyframe, then drag the little circle that appears up or down to set the value you want. Repeat for as many keyframes as you like. I don't like it because the control isn't as fine as you get from the Effects Control panel, and because the clip you want to adjust the properties of has to be the one actually selected on the timeline. If you don't have a clip selected or if you have the wrong one on the same track selected, you can really screw things up.

You can do it on any video or audio track, though by default, the bands only show on the first one. You have to twirl open the triangle next to the layer name to see them on layers above the first.